The case component of a power semiconductor device is provided with a nut insertion hole for inserting a nut for receipt of a threaded member, such as a bolt or screw, used to attach the terminal of a wire thereto, and a terminal insertion hole for receipt of the wire therethrough. In a case where it is not possible to secure a sufficient distance between the nut insertion hole and the terminal insertion hole, the intermediate wall between the nut insertion and terminal insertion holes becomes thin. As a result, the intermediate wall may not withstand the pressure of a flank or side of the nut bearing thereagainst during screwing of the bolt or screw into the nut, and be damaged. Further, even in a case where a groove for increasing a creepage distance is disposed around the nut insertion hole, the thin intermediate wall adjoins the nut insertion hole, and thus the intermediate wall may be damaged.